Chronological changes of clinical characteristics in 31,115 new breast cancer patients among Koreans during 1996-2004.

Breast cancer has emerged as the most frequent malignancy among Korean women. Its clinical features have become closer to those now observed in Western countries. We performed this study to evaluate the chronological changes in Korean breast cancer characteristics and reproductive factors from 1996 to 2004. A nationwide multi-center survey within the Korean Breast Cancer Society (KBCS) has been performed since 1996. We analyzed the chronological changes among newly diagnosed primary breast cancer patients recruited at 41 university- and 65 surgical training-hospitals. All participating hospitals provided the essential information, including sex, age, surgical method used, American Joint Committee on Cancer classification, and other information, including reproductive factors, etc. This study showed a continuous increase in: the incidence of breast cancer (154.3% increase from 3801 to 9667 patients); breast-conserving surgery (124.1% increase from 18.7 to 41.9%); breast reconstruction after operation (25.4% increase from 5.2 to 16.4%); the percentage of early cancer (128.6% increase for stage 0; a 64.8% increase for stage I); and the number of patients with reproductive factors, such as early menarche, late menopause, late first-delivery, and no breast feeding. These results suggest that the rate of breast cancer in Korea is expected to continuously increase in the future; and that the pattern of breast cancer is perhaps mirroring that observed in Western countries.